**************************************************************************
USACE / NAVFAC / AFCEC / NASA
UFGS-26 28 00.00 10 (October 2007)
---------------------------------Preparing Activity: USACE
Superseding
UFGS-26 28 00.00 10 (April 2006)
UNIFIED FACILITIES GUIDE SPECIFICATIONS
References are in agreement with UMRL dated January 2016
**************************************************************************
SECTION TABLE OF CONTENTS
DIVISION 26 - ELECTRICAL
SECTION 26 28 00.00 10
MOTOR CONTROL CENTERS, SWITCHBOARDS AND PANELBOARDS
10/07
PART 1
GENERAL
1.1
SUMMARY
1.2
REFERENCES
1.3
SUBMITTALS
1.4
DELIVERY, STORAGE, AND HANDLING
1.5
MAINTENANCE
1.5.1
Accessories and Tools
1.5.2
Extra Materials
PART 2
PRODUCTS
2.1
MATERIALS AND EQUIPMENT
2.1.1
Rules
2.1.2
Coordination
2.2
NAMEPLATES
2.3
CONNECTIONS
2.4
MOLDED CASE CIRCUIT BREAKERS
2.4.1
Trip Units
2.4.2
480-Volt AC Circuits
2.4.3
120/240-Volt AC Circuits
2.4.4
125-Volt DC Circuits
2.5
WIRING
2.6
TERMINAL BLOCKS
2.6.1
Types of Terminal Blocks
2.6.1.1
Short-Circuiting Type
2.6.1.2
Load Type
2.6.2
Marking Strips
2.7
SPACE HEATERS
2.8
MOTOR CONTROL CENTERS
2.8.1
Enclosures
2.8.1.1
Unit Compartments
2.8.1.2
Motor Control Center Doors and Covers
2.8.1.3
Horizontal Wireways
2.8.1.4
Vertical Wireways
2.8.1.5
Sills
SECTION 26 28 00.00 10
Page 1
2.8.1.6
NEMA 3R Enclosures
2.8.1.7
Shutters
2.8.1.8
[Thermostatically Controlled Strip Heaters
2.8.2
Buses
2.8.2.1
Horizontal Bus
2.8.2.2
Vertical Bus
2.8.2.3
[Ground Bus
2.8.2.4
[Neutral Bus
2.8.3
Combination Starters
2.8.3.1
Magnetic Contactors
2.8.3.2
[Reduced Voltage Starters
2.8.3.3
Auxiliary Contacts
2.8.3.4
Overload Relays
2.8.3.5
[Individual Control Transformers
2.8.3.6
[Voltage Fault Protection
2.8.3.7
Control Circuit Disconnects
2.8.4
Molded Case Circuit Breakers in Unit Compartments
2.8.5
Panelboards for Motor Control Centers
2.8.6
Distribution Transformers
2.8.7
[Ground Detector Indicator
2.8.8
Wiring for Motor Control Centers
2.8.8.1
Contractor's Wiring
2.8.8.2
External Connections
2.8.8.3
Terminal Blocks
2.8.9
[Control Transformers
2.8.10
Accessories and Control Devices
2.8.10.1
Control Stations
2.8.10.2
LED Indicating Lights
2.8.10.3
Control Relays
2.8.10.4
Timing Relays
2.8.10.5
Alternators
2.8.10.6
Elapsed-Time Meters
2.8.11
Feeder Tap Units
2.8.12
Metering Section
2.8.12.1
Instrument Transformers
2.8.12.2
Ammeters
2.8.12.3
Voltmeters
2.8.12.4
Watthour Meters
2.8.12.5
Switches
2.8.13
[Power-Factor-Correction Capacitors
2.8.14
[Space for Mounting PLC's
2.9
SWITCHBOARDS
2.9.1
Enclosure
2.9.2
Bus
2.9.3
[Grounding Bus
2.9.4
Components
2.10
PANELBOARDS
2.10.1
Enclosure
2.10.2
Buses
2.10.3
Components
2.11
FACTORY TESTS
2.11.1
Motor Control Centers Tests
2.11.1.1
Dielectric Tests
2.11.1.2
Operational Tests
2.11.1.3
Short Circuit Tests
2.11.2
Switchboards Tests
2.11.2.1
Production Tests
2.11.2.2
Short Circuit Tests
2.11.3
Panelboards Tests
SECTION 26 28 00.00 10
Page 2
2.12
PART 3
PAINTING
EXECUTION (Not Applicable)
-- End of Section Table of Contents --
SECTION 26 28 00.00 10
Page 3
**************************************************************************
USACE / NAVFAC / AFCEC / NASA
UFGS-26 28 00.00 10 (October 2007)
---------------------------------Preparing Activity: USACE
Superseding
UFGS-26 28 00.00 10 (April 2006)
UNIFIED FACILITIES GUIDE SPECIFICATIONS
References are in agreement with UMRL dated January 2016
**************************************************************************
SECTION 26 28 00.00 10
MOTOR CONTROL CENTERS, SWITCHBOARDS AND PANELBOARDS
10/07
**************************************************************************
NOTE: This guide specification covers the
requirements for motor control centers, switchboards
and panelboards by formal advertising, using a
SUPPLY-type contract. This section was originally
developed for USACE Civil Works projects.
Adhere to UFC 1-300-02 Unified Facilities Guide
Specifications (UFGS) Format Standard when editing
this guide specification or preparing new project
specification sections. Edit this guide
specification for project specific requirements by
adding, deleting, or revising text. For bracketed
items, choose applicable items(s) or insert
appropriate information.
Remove information and requirements not required in
respective project, whether or not brackets are
present.
Comments, suggestions and recommended changes for
this guide specification are welcome and should be
submitted as a Criteria Change Request (CCR).
**************************************************************************
PART 1
GENERAL
**************************************************************************
NOTE: This section includes the technical
requirements for the types of equipment provided at
navigation locks and dams, flood control pumping
plants, and hydroelectric power plants to supply
auxiliary power to the power plant, switchyard, dam
and other project facilities.
Applicable portions of this document will be
incorporated into electrical specifications when
equipment is purchased using a CONSTRUCTION-type
contract. Modifications needed to do this will
include: Modifying submittal requirements to
eliminate submittals tied to notice to proceed
SECTION 26 28 00.00 10
Page 4
dates, adding a PART 3 EXECUTION section covering
installation of the equipment, adding installation
material, such as conduit and wire, and quality
information to PART 2 PRODUCTS. Section 26 20 00
INTERIOR DISTRIBUTION SYSTEM may be used as a basis
for the EXECUTION section.
Suitable drawings showing the general arrangement
and single-line diagram of each motor control
center, switchboard, and panelboard should be
included with the procurement specifications. The
drawings should show the locations of conduit and
cable entrances, details of nameplates, and
tabulations showing the NEMA size of contactors and
motor controllers, trip ratings of circuit breakers,
solid state trips where required, alarm and bell
contacts and shunt trips where required, sizes of
feeder and branch circuit conductors, and ratings of
motors and other loads.
This specification covers NEMA Class II motor
control centers where interlocking and remote
control are required as is engineering effort on the
part of the manufacturer. Where cost savings may be
realized by grouping motor controls together, but
where motor operations are not interlocked, locally
or remotely, and no manufacturer's engineering
effort required, NEMA Class I should be used. This
specification may be modified for NEMA Class I motor
control centers by deleting the following paragraphs
from PART 2:
WIRING (except when applicable to switchboards)
TERMINAL BLOCKS (except when applicable to
switchboards)
MOTOR CONTROL CENTERS - change references to Class
II, type B and C.
Horizontal Wireways - the option for mater terminal
block compartment should generally not be included.
Wiring for Motor Control Centers
Alternators
Operational Tests
**************************************************************************
1.1
SUMMARY
**************************************************************************
NOTE: Drafts of specifications submitted to higher
authority for review and approval will consist of
printed copies of this guide specification combined
with pertinent sections of procurement documents as
call for on Standard Form 33, both revised as
required for the particular procurement.
SECTION 26 28 00.00 10
Page 5
be deleted from this section of the project
specification when you choose to reconcile
references in the publish print process.
**************************************************************************
The publications listed below form a part of this specification to the
extent referenced. The publications are referred to within the text by the
basic designation only.
ASME INTERNATIONAL (ASME)
ASME B1.1
(2003; R 2008) Unified Inch Screw Threads
(UN and UNR Thread Form)
ASME B1.20.1
(2013) Pipe Threads, General Purpose (Inch)
ASME B1.20.2M
(2006; R 2011) Pipe Threads, 60 Deg.
General Purpose (Metric)
ASTM INTERNATIONAL (ASTM)
ASTM B187/B187M
(2015) Standard Specification for Copper,
Bus Bar, Rod and Shapes and General
Purpose Rod, Bar and Shapes
ASTM B317/B317M
(2007) Standard Specification for
Aluminum-Alloy Extruded Bar, Rod, Tube,
Pipe, and Structural Profiles for
Electrical Purposes (Bus Conductor)
INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS (IEEE)
IEEE C57.13
(2008; INT 2009) Standard Requirements for
Instrument Transformers
NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION (NEMA)
ANSI C12.1
(2008) Electric Meters Code for
Electricity Metering
NEMA C12.4
(1984; R 2011) Registers - Mechanical
Demand
NEMA ICS 1
(2000; R 2015) Standard for Industrial
Control and Systems: General Requirements
NEMA ICS 2
(2000; R 2005; Errata 2008) Standard for
Controllers, Contactors, and Overload
Relays Rated 600 V
NEMA ICS 4
(2015) Terminal Blocks
NEMA ICS 6
(1993; R 2011) Enclosures
NEMA PB 1
(2011) Panelboards
NEMA PB 2
(2011) Deadfront Distribution Switchboards
NEMA ST 1
(1988; R 1994; R 1997) Specialty
SECTION 26 28 00.00 10
Page 7
be deleted from this section of the project
specification when you choose to reconcile
references in the publish print process.
**************************************************************************
The publications listed below form a part of this specification to the
extent referenced. The publications are referred to within the text by the
basic designation only.
ASME INTERNATIONAL (ASME)
ASME B1.1
(2003; R 2008) Unified Inch Screw Threads
(UN and UNR Thread Form)
ASME B1.20.1
(2013) Pipe Threads, General Purpose (Inch)
ASME B1.20.2M
(2006; R 2011) Pipe Threads, 60 Deg.
General Purpose (Metric)
ASTM INTERNATIONAL (ASTM)
ASTM B187/B187M
(2015) Standard Specification for Copper,
Bus Bar, Rod and Shapes and General
Purpose Rod, Bar and Shapes
ASTM B317/B317M
(2007) Standard Specification for
Aluminum-Alloy Extruded Bar, Rod, Tube,
Pipe, and Structural Profiles for
Electrical Purposes (Bus Conductor)
INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS (IEEE)
IEEE C57.13
(2008; INT 2009) Standard Requirements for
Instrument Transformers
NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION (NEMA)
ANSI C12.1
(2008) Electric Meters Code for
Electricity Metering
NEMA C12.4
(1984; R 2011) Registers - Mechanical
Demand
NEMA ICS 1
(2000; R 2015) Standard for Industrial
Control and Systems: General Requirements
NEMA ICS 2
(2000; R 2005; Errata 2008) Standard for
Controllers, Contactors, and Overload
Relays Rated 600 V
NEMA ICS 4
(2015) Terminal Blocks
NEMA ICS 6
(1993; R 2011) Enclosures
NEMA PB 1
(2011) Panelboards
NEMA PB 2
(2011) Deadfront Distribution Switchboards
NEMA ST 1
(1988; R 1994; R 1997) Specialty
SECTION 26 28 00.00 10
Page 7
Transformers (Except General Purpose Type)
NEMA ST 20
(1992; R 1997) Standard for Dry-Type
Transformers for General Applications
NEMA/ANSI C12.10
(2011) Physical Aspects of Watthour Meters
- Safety Standards
NEMA/ANSI C12.11
(2007) Instrument Transformers for Revenue
Metering, 10 kV BIL through 350 kV BIL
(0.6 kV NSV through 69 kV NSV)
NATIONAL FIRE PROTECTION ASSOCIATION (NFPA)
NFPA 70
(2014; AMD 1 2013; Errata 1 2013; AMD 2
2013; Errata 2 2013; AMD 3 2014; Errata
3-4 2014; AMD 4-6 2014) National
Electrical Code
UNDERWRITERS LABORATORIES (UL)
UL 1063
(2006; Reprint Jul 2012) Machine-Tool
Wires and Cables
UL 44
(2014; Reprint Feb 2015)
Thermoset-Insulated Wires and Cables
UL 489
(2013; Reprint Mar 2014) Molded-Case
Circuit Breakers, Molded-Case Switches,
and Circuit-Breaker Enclosures
UL 50
(2007; Reprint Apr 2012) Enclosures for
Electrical Equipment, Non-environmental
Considerations
UL 67
(2009; Reprint Apr 2015) Standard for
Panelboards
UL 845
(2005; Reprint Jul 2011) Motor Control
Centers
UL 891
(2005; Reprint Oct 2012) Switchboards
1.3
SUBMITTALS
**************************************************************************
NOTE: Review submittal description (SD) definitions
in Section 01 33 00 SUBMITTAL PROCEDURES and edit
the following list to reflect only the submittals
required for the project.
The Guide Specification technical editors have
designated those items that require Government
approval, due to their complexity or criticality,
with a "G." Generally, other submittal items can be
reviewed by the Contractor's Quality Control
System. Only add a “G” to an item, if the submittal
is sufficiently important or complex in context of
the project.
SECTION 26 28 00.00 10
Page 8
For submittals requiring Government approval on Army
projects, a code of up to three characters within
the submittal tags may be used following the "G"
designation to indicate the approving authority.
Codes for Army projects using the Resident
Management System (RMS) are: "AE" for
Architect-Engineer; "DO" for District Office
(Engineering Division or other organization in the
District Office); "AO" for Area Office; "RO" for
Resident Office; and "PO" for Project Office. Codes
following the "G" typically are not used for Navy,
Air Force, and NASA projects.
An "S" following a submittal item indicates that the
submittal is required for the Sustainability
Notebook to fulfill federally mandated sustainable
requirements in accordance with Section 01 33 29
SUSTAINABILITY REPORTING.
Choose the first bracketed item for Navy, Air Force
and NASA projects, or choose the second bracketed
item for Army projects.
**************************************************************************
Government approval is required for submittals with a "G" designation;
submittals not having a "G" designation are for [Contractor Quality Control
approval.][information only. When used, a designation following the "G"
designation identifies the office that will review the submittal for the
Government.] Submittals with an "S" are for inclusion in the
Sustainability Notebook, in conformance to Section 01 33 29 SUSTAINABILITY
REPORTING. Submit the following in accordance with Section 01 33 00
SUBMITTAL PROCEDURES:
SD-02 Shop Drawings
Drawings; G[, [_____]]
Shop Drawings; G[, [_____]]
Motor Control Centers; G[, [_____]]
Switchboards; G[, [_____]]
Panelboards; G[, [_____]]
SD-03 Product Data
Equipment; G[, [_____]]
Factory Tests
SD-06 Test Reports
Factory Tests
SD-07 Certificates
Motor Control Centers
1.4
DELIVERY, STORAGE, AND HANDLING
**************************************************************************
NOTE: ABC phasing should be in accordance with NFPA
SECTION 26 28 00.00 10
Page 9
70 front-to-back, top-to-bottom, and left-to-right.
Alternate phasing should be avoided, but where this
cannot be done, the drawings should clearly reflect
alternate phasing, and these specifications be
modified to include requirement for marking the
equipment.
**************************************************************************
Submit [6] [_____] copies of such descriptive cuts and information as are
required to demonstrate fully that all parts of the equipment will conform
to the requirements and intent of the specifications, within [30] [_____]
calendar days after [date of award] [date of receipt of notice to proceed]
for approval. Data shall include descriptive data showing typical
construction of the types of equipment proposed, including the
manufacturer's name, type of molded case circuit breakers or motor circuit
protectors, performance capacities and other information pertaining to the
equipment. [Also [6] [_____] sets of characteristic curves of the
individual breaker trip element.] Ship the equipment as completely
assembled and wired as feasible so as to require a minimum of installation
work. Each shipping section shall be properly match marked to facilitate
reassembly, and shall be provided with removable lifting channels with eye
bolts for attachment of crane slings to facilitate lifting and handling.
Any relay or other device which cannot withstand the hazards of shipment
when mounted in place on the equipment shall be carefully packed and
shipped separately. These devices shall be marked with the number of the
panel which they are to be mounted on and fully identified. All finished
painted surfaces and metal work shall be wrapped suitably or otherwise
protected from damage during shipment. All parts shall be prepared for
shipment so that slings for handling may be attached readily while the
parts are in a railway car or transport truck. [Sections of equipment
crated for shipment shall be of such size, including crates, that they will
pass through a [_____] by [_____] -meter -foot hatch opening and a [_____]
by [_____] -meter -foot wall opening.] All spare parts and accessories
shall be carefully packaged and clearly marked.
1.5
1.5.1
MAINTENANCE
Accessories and Tools
Furnish a complete set of accessories and special tools unique to equipment
provided and required for erecting, handling, dismantling, testing and
maintaining the apparatus.
1.5.2
Extra Materials
**************************************************************************
NOTE: If three or more motors of the same size and
manufacturer are required, the designer should
specify more spare heater elements.
**************************************************************************
Furnish spare parts as specified below. All spare parts shall be of the
same material and workmanship, shall meet the same requirements, and shall
be interchangeable with the corresponding original parts furnished.
SECTION 26 28 00.00 10
Page 10
SPARE PARTS
PART 2
2.1
Amount
Description
2 of each type and size
Fuses
1
Circuit breaker auxiliary switch
2 for each size ac contactor
Operating coils
1 for each size dc contactor
Operating coil
2 Complete sets for each
size ac contactor
3-pole stationary and moving contact assemblies
1 Complete set for each size
dc contactor
2-pole stationary and moving contact assemblies
3 of each type and rating
Contactor overload relays, each relay with a
complete set of contact blocks
1 Spare set for each heater
rating provided
Heater elements
2 for each type
Indicating lamp assemblies
1 of each type and rating
Control transformer
1 of each type and rating
Control relay
1 of each type
Contactor auxiliary contact
4 One quart containers
Finish paint for indoor equipment
2 One quart containers
Paint used for the exterior surfaces of outdoor
equipment
4
Keys for motor control center door loc
PRODUCTS
MATERIALS AND EQUIPMENT
Provide materials and equipment which are standard products of a
manufacturer regularly engaged in their manufacture and that essentially
duplicate items that have been in satisfactory use for at least 2 years
prior to bid opening and that conform to the requirements of these
specifications. Materials shall be of high quality, free from defects and
imperfections, of recent manufacture, and of the classification and grades
designated. All materials, supplies, and articles not manufactured by the
Contractor shall be the products of other recognized reputable
manufacturers.
2.1.1
Rules
**************************************************************************
NOTE: Many manufacturers represent IEC ratings as
equivalent to NEMA ratings or UL labeling. The two
are different standards philosophies and are not
interchangeable. IEC ratings are not acceptable
SECTION 26 28 00.00 10
Page 11
designations used on the Contractor's wiring diagrams and printed on
terminal block marking strips may be according to the Contractor's standard
practice; however, additional wire and cable designations for
identification of remote (external) circuits shall be provided for the
Government's wire designations. Drawings shall show the general
arrangement and overall dimensions of the motor control centers,
switchboards, and panelboards. These drawings shall show space
requirements, details of any floor supports to be embedded in concrete and
provisions for conduits for external cables. Prints of drawings submitted
for approval will be so marked and returned to the Contractor for addition
of the designations to the terminal strips and tracings, along with any
rearrangement of points required.
2.7
SPACE HEATERS
**************************************************************************
NOTE: Heaters should be connected to an external
power source in installations where the motor
control center will not be energized continuously.
**************************************************************************
Space heaters shall be provided where indicated on the drawings and shall
be controlled using an adjustable 10 to 35 degrees C 50 to 90 degrees F
thermostat, magnetic contactor, and a molded-case circuit breaker [and a
480-120 volt single-phase transformer]. The space heaters shall be
250-watt, 240 volt strip elements operated at 120 volts and shall be
[supplied from the motor control center bus] [wired to terminal blocks for
connection to 120-volt single-phase power sources located external to the
control centers]. The contactors shall be open type, electrically-held,
rated 30 amperes, 2-pole, with 120-volt ac coils.
2.8
MOTOR CONTROL CENTERS
**************************************************************************
NOTES: This specification covers single stand alone
lineup with front access. Not all arrangements can
be listed and labeled under UL 845. Consult
manufacturer's literature and UL listing
availability for specific arrangements.
Auxiliary motor control centers should be NEMA Class
II, Type B or C, as applicable. Type C construction
includes master section terminal boards at the top
or bottom of each vertical section and complete
control wiring and power wiring for NEMA Size 3 and
smaller controllers between the unit assemblies in
each section and the master terminal boards. Type C
construction is preferred and should be specified
whenever a considerable amounts of interpanel
control wiring or external control circuits is
required. Designer should consider number of
terminal blocks required for type C construction and
ensure that there is sufficient space and access.
Where the unit assemblies consist primarily of
feeder tap units with circuit breakers to supply
power loads or starter units for individually
controlled motors (such as for pumps in pumping
stations), and very little interpanel and external
SECTION 26 28 00.00 10
Page 16
control wiring is required, the less expensive Type
B construction, which does not include master
section terminal boards, should be specified. If
the procurement includes both types of control
centers, the type of each control center should be
clearly indicated.
The intent of the submittals below is to require
NEMA Class II drawing packages. When it is
desirable for the Government's wire numbers to be
included on the drawings or custom drawing sizes and
title blocks are required, NEMA Class IIS should be
specified.
Should this specification be used in procurement of
NEMA Class I equipment, the drawing packages are
less involved and this paragraph edited accordingly.
Include this requirement only when contractual
certification is required and Factory Test Reports
without certification are not acceptable.
**************************************************************************
Each motor control center shall be designed for operation on 480-volts ac,
3-phase, 60-Hz system, and the equipment shall conform to all the
applicable requirements of NEMA ICS 1, NEMA ICS 2, NEMA ICS 4and NEMA ICS 6.
Vertical sections and individual units shall be listed and labeled under
UL 845 where ever possible. In lieu of the UL listing, certification from
any nationally recognized, adequately equipped, testing agency that the
individual units and vertical sections have been tested and conform to the
UL requirements of that agency will be acceptable when approved by the
Contracting Officer.
a.
Certification of factory test reports. Certification shall be signed
by official authorized to certify on behalf of the manufacturer,
attesting that the motor control center meets the specified
requirements. The statement shall be dated after the award of this
contract, shall state the Contractor's name and address, shall name the
project and location, and shall list the specific requirements which
are being certified.
b.
The motor control center shall be NEMA Class II, [Type B] [Type C]
[Type B or C as indicated in the bid item list], motor control centers
in accordance with NEMA ICS 2. Submit [6] [_____] copies of electrical
equipment drawings, within [30] [_____] calendar days after [date of
award] [date of receipt of notice to proceed], for the approval of the
Contracting Officer. [The NEMA Class II[S] motor control center
drawings shall include a connection diagram with wire designations and
schematic diagrams to illustrate operation of associated motor unit
controls.]
c.
Submit an individual wiring diagram for each motor control center.
[Wiring diagrams shall be in a form showing physical arrangement of the
control center with interconnecting wiring shown by lines or by
terminal designations (wireless).] Provide a single-line diagram,
equipment list and nameplate schedule for each switchboard and
panelboard.
SECTION 26 28 00.00 10
Page 17
latch operated by means of a keyed handle. Steel sheets and doors shall be
not less than 3.5 mm No. 10 gage thick and doors shall have bent angle or
channel edges with all corner seams welded and ground smooth. The motor
control center within the enclosure shall be assembled with adequate
gaskets and structure to assure a measure of vandal resistance.
Ventilating openings and an effective insulating air space of approximately
50 mm 2 inches shall be provided below the roof of the structure which
shall slope from front to back for adequate drainage. The outside edges of
the control center base shall permit easy sealing at the concrete surface
with mastic compound. A 200-watt outdoor lighting fixture with globe and
guard shall be furnished to light the front of the assembly. All lighting
connections shall be watertight. A weatherproof switch installation shall
be furnished on the front or side of the enclosure so that the light can be
switched prior to opening the assembly doors. The exterior manual switch
shall be "ac" rated, 15 amperes, 120/277 volts. Two duplex receptacle
units shall be provided within the outer weatherproof enclosure. The
lighting fixture and receptacles shall be wired to the 120-volt ac
panelboard located in the control center, and external wiring shall be run
in rigid galvanized steel conduit.
2.8.1.7
Shutters
Drawout units shall have shutters which close when the unit is withdrawn to
isolate the vertical bus.
2.8.1.8
[Thermostatically Controlled Strip Heaters
**************************************************************************
NOTE: Delete this paragraph when not required.
**************************************************************************
Thermostatically controlled strip heaters as specified in paragraph SPACE
HEATERS shall be provided [in all motor control centers] [where indicated].]
2.8.2
Buses
**************************************************************************
NOTES: When either copper of aluminum bus are
allowed the manufacturers will generally provide the
less expensive aluminum. Use ASTM 317 when aluminum
bus is permitted.
NEMA ICS 2 allows a 65 degrees C 117 degrees F
temperature rise on the buses, irrespective of the
equipment used. UL 845 allows 65 degrees C 117
degrees F temperature rise only under certain
conditions. In general this means all buses must be
plated and devices must be UL labeled for the higher
temperatures. If this is not the case, the UL
standard for temperature rise is 50 degrees C 90
degrees F creating a conflict with NEMA. The
designer should be aware of this difference. This
specification references the UL standard and bases
the rise on the exceptions it permits.
**************************************************************************
All buses shall be of copper [or aluminum] and [all bolted splices and
connections between buses and for extensions or taps for equipment shall be
tin or silver-plated] [shall be tin or silver-plated throughout]. Copper
SECTION 26 28 00.00 10
Page 20
[or aluminum] bars and shapes for bus conductors shall conform to the
applicable requirements of ASTM B187/B187M [, and ASTM B317/B317M]. All
splices for field assembly shall be bolted with at least two bolts and
shall employ the use of "Belleville" washers in the connection. The bus
ratings shall be based on a 65 degree Celsius maximum temperature rise in
accordance with UL 845 requirements. Bus shall have a short-circuit
current rating of not less than [42,000] [65,000] [100,000] RMS symmetrical
amperes. All bus work shall be supported on wet process porcelain
insulators, glass polyester, or suitable molded material.
2.8.2.1
Horizontal Bus
Each control center assembly shall be provided with a three-phase main
horizontal bus, with a continuous current rating not less than [600] [800]
[1,000] [1,200] amperes, located across the top of each vertical section.
The ends of horizontal buses shall be drilled for future extensions. [The
main horizontal bus shall be fully insulated.]
2.8.2.2
Vertical Bus
Each vertical section shall be provided with a three-phase vertical bus
with a continuous current rating of [300] [600] amperes connected to the
horizontal bus by brazing, welding, or bolting. Where the incoming feeder
breakers are located at the bottom of a control center, the vertical bus in
that section shall be rated the same as the main horizontal bus. Vertical
buses shall extend from the horizontal bus to the bottom of the lowest
available unit mounting space. The vertical bus shall be isolated from
wireways and equipment in compartments.
2.8.2.3
[Ground Bus
**************************************************************************
NOTE: Delete this paragraph when not required.
**************************************************************************
A copper [or aluminum] ground bus shall be provided full width at the
bottom of the motor control center line-up. A full clamp-type solderless
copper or copper alloy lug for No. 2/0 AWG stranded copper cable shall be
provided at each end of the bus for connection to the station grounding
system.]
2.8.2.4
[Neutral Bus
**************************************************************************
NOTE: Delete this paragraph when not required.
**************************************************************************
A [half] [fully] rated neutral bus shall be furnished continuous through
the control center. Lugs of appropriate capacity will be furnished.]
2.8.3
Combination Starters
**************************************************************************
NOTES: The minimum bus short-circuit rating for
most manufacturers is 42,000 amps rms symmetrical.
Most combination starters without current limiting
type circuit breakers or motor circuit protectors
have a short circuit rating of 25,000 amps. The
designer shall evaluate the available short circuit
SECTION 26 28 00.00 10
Page 21
designations used on the Contractor's wiring diagrams and printed on
terminal block marking strips may be according to the Contractor's standard
practice; however, additional wire and cable designations for
identification of remote (external) circuits shall be provided for the
Government's wire designations. Drawings shall show the general
arrangement and overall dimensions of the motor control centers,
switchboards, and panelboards. These drawings shall show space
requirements, details of any floor supports to be embedded in concrete and
provisions for conduits for external cables. Prints of drawings submitted
for approval will be so marked and returned to the Contractor for addition
of the designations to the terminal strips and tracings, along with any
rearrangement of points required.
2.7
SPACE HEATERS
**************************************************************************
NOTE: Heaters should be connected to an external
power source in installations where the motor
control center will not be energized continuously.
**************************************************************************
Space heaters shall be provided where indicated on the drawings and shall
be controlled using an adjustable 10 to 35 degrees C 50 to 90 degrees F
thermostat, magnetic contactor, and a molded-case circuit breaker [and a
480-120 volt single-phase transformer]. The space heaters shall be
250-watt, 240 volt strip elements operated at 120 volts and shall be
[supplied from the motor control center bus] [wired to terminal blocks for
connection to 120-volt single-phase power sources located external to the
control centers]. The contactors shall be open type, electrically-held,
rated 30 amperes, 2-pole, with 120-volt ac coils.
2.8
MOTOR CONTROL CENTERS
**************************************************************************
NOTES: This specification covers single stand alone
lineup with front access. Not all arrangements can
be listed and labeled under UL 845. Consult
manufacturer's literature and UL listing
availability for specific arrangements.
Auxiliary motor control centers should be NEMA Class
II, Type B or C, as applicable. Type C construction
includes master section terminal boards at the top
or bottom of each vertical section and complete
control wiring and power wiring for NEMA Size 3 and
smaller controllers between the unit assemblies in
each section and the master terminal boards. Type C
construction is preferred and should be specified
whenever a considerable amounts of interpanel
control wiring or external control circuits is
required. Designer should consider number of
terminal blocks required for type C construction and
ensure that there is sufficient space and access.
Where the unit assemblies consist primarily of
feeder tap units with circuit breakers to supply
power loads or starter units for individually
controlled motors (such as for pumps in pumping
stations), and very little interpanel and external
SECTION 26 28 00.00 10
Page 16
control wiring is required, the less expensive Type
B construction, which does not include master
section terminal boards, should be specified. If
the procurement includes both types of control
centers, the type of each control center should be
clearly indicated.
The intent of the submittals below is to require
NEMA Class II drawing packages. When it is
desirable for the Government's wire numbers to be
included on the drawings or custom drawing sizes and
title blocks are required, NEMA Class IIS should be
specified.
Should this specification be used in procurement of
NEMA Class I equipment, the drawing packages are
less involved and this paragraph edited accordingly.
Include this requirement only when contractual
certification is required and Factory Test Reports
without certification are not acceptable.
**************************************************************************
Each motor control center shall be designed for operation on 480-volts ac,
3-phase, 60-Hz system, and the equipment shall conform to all the
applicable requirements of NEMA ICS 1, NEMA ICS 2, NEMA ICS 4and NEMA ICS 6.
Vertical sections and individual units shall be listed and labeled under
UL 845 where ever possible. In lieu of the UL listing, certification from
any nationally recognized, adequately equipped, testing agency that the
individual units and vertical sections have been tested and conform to the
UL requirements of that agency will be acceptable when approved by the
Contracting Officer.
a.
Certification of factory test reports. Certification shall be signed
by official authorized to certify on behalf of the manufacturer,
attesting that the motor control center meets the specified
requirements. The statement shall be dated after the award of this
contract, shall state the Contractor's name and address, shall name the
project and location, and shall list the specific requirements which
are being certified.
b.
The motor control center shall be NEMA Class II, [Type B] [Type C]
[Type B or C as indicated in the bid item list], motor control centers
in accordance with NEMA ICS 2. Submit [6] [_____] copies of electrical
equipment drawings, within [30] [_____] calendar days after [date of
award] [date of receipt of notice to proceed], for the approval of the
Contracting Officer. [The NEMA Class II[S] motor control center
drawings shall include a connection diagram with wire designations and
schematic diagrams to illustrate operation of associated motor unit
controls.]
c.
Submit an individual wiring diagram for each motor control center.
[Wiring diagrams shall be in a form showing physical arrangement of the
control center with interconnecting wiring shown by lines or by
terminal designations (wireless).] Provide a single-line diagram,
equipment list and nameplate schedule for each switchboard and
panelboard.
SECTION 26 28 00.00 10
Page 17
2.8.1
Enclosures
**************************************************************************
NOTES: Stand alone front access line-ups are most
desirable for ease of operation and maintenance, but
particular installations may require specialized
arrangements, such as back-to-back mounted units.
Consult manufacturers for specialized requirements.
NFPA 70 Article 430H lists the various NEMA
enclosure types for Motor Control Centers. Designer
should ensure that the NEMA type specified meets
design requirements.
**************************************************************************
Each motor control center shall consist of the required number of vertical
sections of 2250 mm 90 inches nominal height, bolted together, with steel
channel sills and suitable for mounting against a wall. Vertical section
shall be 510 mm 20 inches deep and buses, control wiring, control
transformers, small power transformers, terminal blocks, line terminals,
cable supports, and clamps shall be accessible from the front. Enclosure
shall be NEMA Type [1 gasketed] [12] [3R]. The control centers shall be
fabricated from smooth select steel sheets shaped and reinforced to form
rigid free-standing structures. Metal thickness for enclosures shall be
not less than specified in NEMA ICS 6 without exception. Vertical edges of
sections exposed to view shall be so fabricated and bolted that the joints
will not pass a 1.6 mm 1/16 inch gage. Each structure shall be designed
for addition of future sections required. Individual compartments shall be
isolated from adjacent compartments.
2.8.1.1
Unit Compartments
Each operating unit shall contain equipment as shown on the drawings,
mounted in an individual cell. The unit assembly, except main circuit
breakers, panelboards and auxiliary control devices, shall be drawout type
removed from the front, without rear access or disturbing other units in
the control center assembly. All drawout type unit assemblies shall have
positive guide rail system to ensure alignment of connection to vertical
bus. Units shall be mechanically interlocked with the door to prevent
removal while in the energized position. Each removable unit shall have
provision for padlocking in a position in which it is disconnected from the
vertical bus although not removed from the stationary structure. All
ventilating openings shall be provided with corrosion-resistant
insect-proof screens on the inside. Bus closing plugs shall be provided
for all unused openings in vertical bus barriers.
2.8.1.2
Motor Control Center Doors and Covers
Each unit compartment, including blank compartments for future use, shall
be provided with either a flange-formed or a rolled-edge door. Each door
shall be mounted on fully-concealed or continuous full-length piano-type
hinges and shall be provided with positive fasteners. Door sag shall be
prevented by proper alignment of hinges made of sufficiently strong
material. The door fastenings shall be so interlocked to prevent opening
when the equipment is energized. The external operating handle shall
clearly indicate whether the equipment is in an "ON", "OFF" or "TRIPPED"
position.
SECTION 26 28 00.00 10
Page 18
NEMA ST 20. Each transformer shall be protected on the primary side with a
molded case circuit breaker as indicated on the drawings. [Transformers
shall be drawout type.]
2.8.7
[Ground Detector Indicator
**************************************************************************
NOTE: Ground detectors requirements should be
evaluated and this paragraph deleted when not
required.
**************************************************************************
Ground-detector indicator (GDI) shall be rated 120-volts; have three lamps,
one per phase, three 480-120 volt transformers connected delta-wye,
adjustable loading resistor for balancing capacitive charging current, and
push-to test-switch. GDI shall provide visual indication of a single
ground-fault on any phase (A, B, or C) of a three-phase, three-wire
ungrounded power system. When no phase is grounded, all lamps shall glow
at partial brightness, giving long lamp life, the push-to test switch shall
not affect the brightness of any lamp. When a single ground-fault occurs
on any phase, the lamp that corresponds to the faulted phase shall be dark
and the other two lamps shall glow at full brightness. The push-to-test
switch shall cause all lamps to return to partial brightness, showing the
GDI is functioning properly.]
2.8.8
Wiring for Motor Control Centers
All wiring shall meet the requirements of paragraph WIRING above. Provide
heavy-duty clamp type terminals for terminating all power cables entering
the control centers.
2.8.8.1
Contractor's Wiring
The Contractor's wiring shall be formed into groups, suitably bound
together, properly supported and run straight horizontally or vertically.
There shall be no splices in the wiring. The manufacturer's standard
pressure-type wire terminations for connections to internal devices will be
acceptable. Terminal blocks shall be added for wiring to devices having
leads instead of terminals. Ring tongue indented terminals shall be used
on all wires terminated on control terminal blocks for external or
interpanel connections and at shipping splits. All stud terminals shall
have contact nuts and either locking nuts or lockwashers.
2.8.8.2
External Connections
**************************************************************************
NOTE: For NEMA 3R enclosures power cables shall
enter from the bottom.
**************************************************************************
Power and control cables will enter the control centers at the [bottom]
[top] [where shown on the drawings]. [Where power and control entry points
are not shown, and terminal blocks are not given on the drawings, the
Government will furnish this information to the Contractor after award of
contract.]
2.8.8.3
Terminal Blocks
Terminal blocks shall meet the requirements of paragraph TERMINAL BLOCKS
SECTION 26 28 00.00 10
Page 26
above. In no case shall the terminals provided for circuit breakers or
contactors accommodate less than the number or size of conductors shown on
the drawings. Special attention shall be given to wiring and terminal
arrangement on the terminal blocks to permit the individual conductors of
each external cable to be terminated on adjacent terminal points.
2.8.9
[Control Transformers
**************************************************************************
NOTE: Delete when individual control transformers
are specified or external control circuit is
provided.
**************************************************************************
Control transformers for several starter units shall be mounted in a
separate compartment and its primary windings shall be connected to the
main bus through a molded case circuit breaker of suitable rating. The
control transformers shall be rated 480-120 volts and shall conform to the
requirements for control transformers in NEMA ST 1. Control transformers
shall have adequate volt-ampere capacity for the control functions
indicated and an additional 10 percent capacity. Transformers shall be
installed without primary fuses. Except as otherwise indicated on the
drawings, each unit compartment shall provide a fuse for control power in
one secondary lead and shall have the other secondary lead grounded. The
unit disconnect shall be equipped with a normally open contact to isolate
the control circuit from the source when the controller disconnect is open.]
2.8.10
Accessories and Control Devices
**************************************************************************
NOTE: Retain only paragraphs for accessories
actually used for a given procurement.
**************************************************************************
Control accessories shall be provided, and shall be suitable for mounting
on the front of, or inside, the control centers as indicated on the
drawings. Control accessories shall meet the applicable requirements of
NEMA ICS 2. Relays and other equipment shall be so mounted that mechanical
vibration will not cause false operation.
2.8.10.1
Control Stations
Push-button stations and selector switches shall conform to NEMA ICS 2,
shall be of the heavy-duty, oil-tight type, rated 600 volts ac, and have a
contact rating designation of A600. Switches shall be provided with
escutcheon plates clearly marked to show operating positions. [Sufficient
contact blocks shall be provided to make up the electrically separate
contacts required for lead-lag selector switches.]
2.8.10.2
LED Indicating Lights
Red and green LED's shall be furnished where shown on the drawings,
indicating contact "open" and "closed" position. The LED's shall be
accessible and replaceable from the front of the control center through a
finished opening in the compartment door. The LED assemblies shall be of
the heavy duty oiltight, watertight, and dusttight type.
SECTION 26 28 00.00 10
Page 27
[or aluminum] bars and shapes for bus conductors shall conform to the
applicable requirements of ASTM B187/B187M [, and ASTM B317/B317M]. All
splices for field assembly shall be bolted with at least two bolts and
shall employ the use of "Belleville" washers in the connection. The bus
ratings shall be based on a 65 degree Celsius maximum temperature rise in
accordance with UL 845 requirements. Bus shall have a short-circuit
current rating of not less than [42,000] [65,000] [100,000] RMS symmetrical
amperes. All bus work shall be supported on wet process porcelain
insulators, glass polyester, or suitable molded material.
2.8.2.1
Horizontal Bus
Each control center assembly shall be provided with a three-phase main
horizontal bus, with a continuous current rating not less than [600] [800]
[1,000] [1,200] amperes, located across the top of each vertical section.
The ends of horizontal buses shall be drilled for future extensions. [The
main horizontal bus shall be fully insulated.]
2.8.2.2
Vertical Bus
Each vertical section shall be provided with a three-phase vertical bus
with a continuous current rating of [300] [600] amperes connected to the
horizontal bus by brazing, welding, or bolting. Where the incoming feeder
breakers are located at the bottom of a control center, the vertical bus in
that section shall be rated the same as the main horizontal bus. Vertical
buses shall extend from the horizontal bus to the bottom of the lowest
available unit mounting space. The vertical bus shall be isolated from
wireways and equipment in compartments.
2.8.2.3
[Ground Bus
**************************************************************************
NOTE: Delete this paragraph when not required.
**************************************************************************
A copper [or aluminum] ground bus shall be provided full width at the
bottom of the motor control center line-up. A full clamp-type solderless
copper or copper alloy lug for No. 2/0 AWG stranded copper cable shall be
provided at each end of the bus for connection to the station grounding
system.]
2.8.2.4
[Neutral Bus
**************************************************************************
NOTE: Delete this paragraph when not required.
**************************************************************************
A [half] [fully] rated neutral bus shall be furnished continuous through
the control center. Lugs of appropriate capacity will be furnished.]
2.8.3
Combination Starters
**************************************************************************
NOTES: The minimum bus short-circuit rating for
most manufacturers is 42,000 amps rms symmetrical.
Most combination starters without current limiting
type circuit breakers or motor circuit protectors
have a short circuit rating of 25,000 amps. The
designer shall evaluate the available short circuit
SECTION 26 28 00.00 10
Page 21
current for a particular installation and place that
value in the space provided.
When short-circuit ratings above 25,000 amps are
required, the designer should consult manufacturer's
data for the availability of non-current limiting
devices at the specific rating and where needed,
show current limiting circuit breakers or motor
circuit protectors the drawings.
In accordance with NEMA ICS 2, the motor control
center short-circuit rating is the maximum available
rms symmetrical current in amperes permissible at
its line terminals which are computed as the sum of
the maximum available current of the system at the
point of connection and the short-circuit current
contribution of the motors connected to the control
center. In the absence of more precise information,
the motor short-circuit current contribution may be
assumed to equal four times the continuous current
rating of the motor control center.
Reduced voltage type starters are specified in the
following paragraph. They should be used in
specialized applications, and indicated on the
drawings. Reduced voltage starting should be
avoided where possible.
This specification does not cover reversing
starters. Where a reversing starter is required,
indicate reversing and non-reversing starters on the
drawings, and modify the specification for clarity.
NEMA sizes are based on continuous duty motors.
Where acceleration time exceeds 10 seconds, or
plugging or jogging duty are required, consult the
manufacturer.
For high efficiency motors, the designer shall
investigate time-current curve characteristics of
the circuit breaker or MCP overcurrent protection to
ensure that the increased starting current of these
motors does not exceed the NFPA 70 standard ratings.
To determine whether to select motor circuit
protectors or molded-case circuit breakers, see
subparagraph Coordination in Part 1.
**************************************************************************
Combination motor controller units shall contain [motor circuit protectors]
[molded-case circuit breakers], auxiliary and pilot devices and [a magnetic
contactor with thermal overload relays] [[or] [and] reduced voltage starter
where indicated on the drawings]. The ratings of [motor circuit
protectors,] air circuit breakers, contactors, motor controllers and other
devices shall be as shown on the drawings. All combination motor
controller units shall have short circuit ratings equal to [_____] or
greater. Where control push-buttons, indicating lamps,
"Hand-Off-Automatic" switches, and similar control devices are associated
with a unit, they shall be mounted on the unit compartment door.
SECTION 26 28 00.00 10
Page 22
Door-mounted components shall not interfere with access within the
compartments. [Molded case circuit breakers for use in combination
starters shall meet the requirements of paragraph MOLDED CASE CIRCUIT
BREAKERS.] [Motor circuit protectors shall be only part of the combination
starters as required by NFPA 70 and shall conform to all requirements of
paragraph MOLDED CASE CIRCUIT BREAKERS, except that trip units shall have
provision for locking the selected trip setting.]
2.8.3.1
Magnetic Contactors
Magnetic contactors shall be of the NEMA sizes indicated on the drawings.
The rating, performance and service characteristics shall conform to the
requirements of NEMA ICS 2 for contactors with continuous current ratings
for the duty indicated. Contactors for motor control shall be rated for
full-voltage starting (Class A controllers). Contactors shall be suitable
for at least 200,000 complete operations under rated load without more than
routine maintenance. The interruption arc and flame shall be minimized by
suitable arc chutes or other means so that no damage will be done to other
portions of the device. The arc chutes, if provided, shall be easily
removable without removing or dismantling other parts. The contacts shall
be easily removable. All current-carrying contact surfaces shall be
silver-surfaced or of other approved material to prevent the formation of
high resistance oxides. The contactor shall operate without chatter or
perceptible hum while energized. Coils shall be suitable for continuous
operation [120-volt ac] [480-volt ac] [125-volt dc] circuits.
Alternating-current contactors shall be three-pole, except where otherwise
noted, and shall be insulated for 600 volts ac and of the electricallyoperated, magnetically-held type. Direct-current contactors shall be
two-pole, suitable for controlling circuits operating at 125 volts dc,
insulated for 250 volts dc, electrically-operated, magnetically-held type
and adequate for full-voltage motor starting service.
2.8.3.2
[Reduced Voltage Starters
**************************************************************************
NOTES: Motor loads using reduced voltage starting
must be able to operate with reduced starting torque.
Autotransformer starters should be used when voltage
drop due to motor starting current is a problem.
Solid state starters may also be used. Designer to
determine best alternative.
Solid state starters provide a smooth acceleration
and are suitable for pump starting. Acceleration
requirements must be coordinated to specific motor.
Delete this paragraph when reduced voltage starters
are not required.
**************************************************************************
[Autotransformers shall be rated for medium duty and have taps according to
NEMA ICS 2. For thermal over load protection, the autotransformer shall
have normally closed thermostat wired in series with the normally closed
thermal overload contact of the starter. Initial connection shall be to
the [65] [_____] percent tap.] [Solid State soft-start starters shall be
three phase SCR controlled for stepless reduced voltage starting of
induction motors.] Current transformers shall provide feedback signal to
regulate torque during start up and to prevent overload conditions while
SECTION 26 28 00.00 10
Page 23
motor is running. Starter shall have starting current of 300 percent of
full load amps for thirty seconds, bypass/isolation contactor, and three
phase thermal overload relay.]
2.8.3.3
Auxiliary Contacts
Each controller shall be provided with a minimum of three auxiliary
contacts which can be easily changed from normally open to normally
closed. Where indicated on the drawings, a fourth auxiliary contact and
red and green indicating lights shall be provided.
2.8.3.4
Overload Relays
**************************************************************************
NOTE: The standard NEMA Class 20 overload relay
operates at 600 percent of its rating after a
maximum of 20 seconds. Other standards are Class 10
and Class 30, operating at a maximum of 10 and 30
seconds. This may be required for special
applications.
**************************************************************************
Except as otherwise indicated, each controller shall be provided three NEMA
Class 20 thermal overload relays with external manual reset. Prior to
shipment of the control centers, the Contracting Officer will furnish the
ratings of the heater elements to be installed in the relays by the
Contractor.
2.8.3.5
[Individual Control Transformers
**************************************************************************
NOTE: Delete this paragraph as well as requirement
for spare control transformer when a single control
transformer for the motor control center is mounted
in a unit compartment or external control source is
provided.
Primary fuses for individual control transformers
are given as an option. For less than 50 VA, they
are not required or desired. Please refer to NFPA
70 section 430-72(c).
**************************************************************************
Where 120 volt ac control of contactors is indicated or required,
individual control transformer shall be provided on the line side of the
unit disconnect. The control transformers shall be rated 480-120 volts and
shall conform to the requirements for control transformers in NEMA ST 1.
Control transformers shall have adequate volt-ampere capacity for the
control functions indicated. Transformers shall be installed [without]
[with] primary fuses. [Primary fuses shall be Class J.] Except as
otherwise indicated on the drawings, each control transformer shall be
provided with a fuse in one secondary lead and shall have the other
secondary lead grounded.]
2.8.3.6
[Voltage Fault Protection
**************************************************************************
NOTE: Voltage fault protection requirements should
be evaluated and this paragraph deleted when not
SECTION 26 28 00.00 10
Page 24
required.
**************************************************************************
Where shown, starters shall be provided with protection against [voltage
faults,] [phase unbalance,] [phase loss,] [phase reversal,] [undervoltage]
[and overvoltage]. Upon sensing one of these faults, the protector shall
de-energize the starter. The protector shall use a combination of voltage
and phase-angle sensing to detect phase loss even when regenerated voltages
are present. The protector shall be connected to the load side of the
motor circuit disconnect. The protector shall have an adjustable line
voltage trip level, adjustable trip delay, automatic reset [and manual
reset by an external normally closed push-button,] and Double Pull Double
Throw (DPDT) output contacts. Protector operation shall have repeatability
of +1 percent of set point, maximum, and a dead band of 2 percent maximum.
Protector shall have green indicator to show normal status and red
indicator to show tripped status. Indicators will be visible through the
compartment door, when LED's are used protector shall be covered with a
clear unbreakable cover, when lamps are used they shall have nameplates and
be grouped with other indicating lights.]
2.8.3.7
Control Circuit Disconnects
**************************************************************************
NOTE: The requirement for disconnect of the control
circuit when the unit compartment is open complies
with NFPA 70 Article 430 F section 430-74.
Generally, manufacturers do not disconnect control
voltage except when racking out the starter unit,
meeting California code, but not NFPA as currently
written. With racking, control circuit voltage is
present when the unit compartment is open, which may
be a safety risk. This paragraph is a specialized
requirement to avoid such a safety hazard. Specific
designs may require a variance. There are available
high density pull apart terminals in the unit
compartments to disconnect control voltage, after
the unit is open. The latter meets the intent of
NFPA, but not the letter. The designer shall
investigate specific project requirements for
interlocking and safety, and modify this paragraph
accordingly.
**************************************************************************
Control circuit power shall disconnect when the unit compartment is opened.
2.8.4
Molded Case Circuit Breakers in Unit Compartments
Molded case circuit breakers for installation in unit compartments shall
meet the requirements of paragraph MOLDED CASE CIRCUIT BREAKERS above.
2.8.5
Panelboards for Motor Control Centers
Panelboards shall meet the requirements of paragraph PANELBOARDS.
2.8.6
Distribution Transformers
Dry type transformers for power and lighting loads shall be furnished with
voltage and kVA ratings as indicated on the drawings. The transformers
shall conform to the requirements for general-purpose transformers in
SECTION 26 28 00.00 10
Page 25
given not less than two coats baked enamel with semigloss finish.
Equipment located indoors shall be ANSI Light Gray, [and equipment located
outdoors shall be ANSI [Light Grey] [Dark Gray].] All touch-up work shall
be done with manufacturer's coatings as supplied under paragraph SPARE
PARTS.
PART 3
EXECUTION (Not Applicable)
**************************************************************************
NOTE: PART 3 will be used for construction
contracts only; take care to prevent conflicts, gaps
or omissions.
**************************************************************************
-- End of Section --
SECTION 26 28 00.00 10
Page 35
above. In no case shall the terminals provided for circuit breakers or
contactors accommodate less than the number or size of conductors shown on
the drawings. Special attention shall be given to wiring and terminal
arrangement on the terminal blocks to permit the individual conductors of
each external cable to be terminated on adjacent terminal points.
2.8.9
[Control Transformers
**************************************************************************
NOTE: Delete when individual control transformers
are specified or external control circuit is
provided.
**************************************************************************
Control transformers for several starter units shall be mounted in a
separate compartment and its primary windings shall be connected to the
main bus through a molded case circuit breaker of suitable rating. The
control transformers shall be rated 480-120 volts and shall conform to the
requirements for control transformers in NEMA ST 1. Control transformers
shall have adequate volt-ampere capacity for the control functions
indicated and an additional 10 percent capacity. Transformers shall be
installed without primary fuses. Except as otherwise indicated on the
drawings, each unit compartment shall provide a fuse for control power in
one secondary lead and shall have the other secondary lead grounded. The
unit disconnect shall be equipped with a normally open contact to isolate
the control circuit from the source when the controller disconnect is open.]
2.8.10
Accessories and Control Devices
**************************************************************************
NOTE: Retain only paragraphs for accessories
actually used for a given procurement.
**************************************************************************
Control accessories shall be provided, and shall be suitable for mounting
on the front of, or inside, the control centers as indicated on the
drawings. Control accessories shall meet the applicable requirements of
NEMA ICS 2. Relays and other equipment shall be so mounted that mechanical
vibration will not cause false operation.
2.8.10.1
Control Stations
Push-button stations and selector switches shall conform to NEMA ICS 2,
shall be of the heavy-duty, oil-tight type, rated 600 volts ac, and have a
contact rating designation of A600. Switches shall be provided with
escutcheon plates clearly marked to show operating positions. [Sufficient
contact blocks shall be provided to make up the electrically separate
contacts required for lead-lag selector switches.]
2.8.10.2
LED Indicating Lights
Red and green LED's shall be furnished where shown on the drawings,
indicating contact "open" and "closed" position. The LED's shall be
accessible and replaceable from the front of the control center through a
finished opening in the compartment door. The LED assemblies shall be of
the heavy duty oiltight, watertight, and dusttight type.
SECTION 26 28 00.00 10
Page 27
2.8.10.3
Control Relays
Control relays shall be of the electrically operated, magnetically held,
self-reset, open type, suitable for mounting inside the starter
compartments, and shall be [125-volt dc] [120-volt ac]. Contacts shall be
as indicated on the drawings and shall have a contact rating designation of
A600 or N600, as required, in accordance with NEMA ICS 2.
2.8.10.4
Timing Relays
Timers shall be pneumatic type. They shall be suitable for mounting inside
the control center and shall be rated 120 volts ac, 60 Hz. Instantaneous
and time delay contacts shall be provided as indicated on the drawings, and
shall have a contact rating designation of A600 or N600, as required, in
accordance with NEMA ICS 2. Means shall be provided for manual adjustment
over a range as indicated on the drawings.
2.8.10.5
Alternators
Alternators 120-volt, 60 Hz, single-phase, open type, suitable for mounting
inside of control center as indicated. Alternators shall automatically
cycle two motor starters in such a manner that No. 1 will lead and No. 2
will lag during the first cycle, and during the second cycle No. 2 will
lead and No. 1 will lag, and the third cycle will repeat the first cycle.
The duration of a cycle will be determined by an [external device]
[adjustable time delay]. Contacts shall have a minimum contact rating
designation of A600 or N600, as required, in accordance with NEMA ICS 2.
2.8.10.6
Elapsed-Time Meters
Hour-indicating time meters shall have 6- digit registers with counter
numbers at least 6 mm 1/4 inch high. White numbers on black backgrounds
shall provide hour indication with the last digit in contrasting colors to
indicate tenths of an hour. The enclosure shall be 90 mm 3-1/2 inches
square and dust resistant. Operating voltage shall be 120 volts ac. They
shall be of the nonreset type.
2.8.11
Feeder Tap Units
Feeder tap units shall be provided as indicated on the drawings.
2.8.12
Metering Section
Metering section shall be provided with instruments as indicated on the
drawings.
2.8.12.1
Instrument Transformers
All transformers used for metering shall meet the requirements of
NEMA/ANSI C12.11 and IEEE C57.13. Voltage transformers shall be protected
with removable primary and secondary fuses. Fuses shall be installed in
each ungrounded lead and located adjacent to the transformers in an easily
accessible place. If cable connections to current transformer primary are
required, terminals of an approved solderless type and proper size shall be
furnished. If current transformers are connected to buses, proper
connections shall be furnished, complete with bolts, nuts, washers and
other accessories.
SECTION 26 28 00.00 10
Page 28
2.8.12.2
Ammeters
Switchboard type ammeter shall be provided where indicated on the drawings.
Ammeter, range 0 to [_____] amperes, complete with selector switch having
off position and positions to read each phase current. Meters shall be
long scale 175 mm 6.8 inches), semiflush rectangular, indicating type
mounted at eye level.
2.8.12.3
Voltmeters
Switchboard type voltmeter shall be provided where indicated on the
drawings. Voltmeter, range 0 to 600 volts, complete with selector switch
having off position and positions to read each phase to phase voltage.
Meters shall be long scale 175 mm 6.8 inches, semiflush rectangular,
indicating type mounted at eye level.
2.8.12.4
Watthour Meters
Watthour meters shall conform to ANSI C12.1 and NEMA/ANSI C12.10, except
numbered terminal wiring sequence and case size may be the manufacturer's
standard. Watthour meters shall be of the drawout switchboard type having
a 15-minute, cumulative form, demand register meeting NEMA C12.4 and
provided with not less than two and one-half stators. [Watthour demand
meters shall have factory installed electronic pulse initiators meeting the
requirements of ANSI C12.1.]
2.8.12.5
Switches
All metering switches shall be of the rotary switchboard type with handles
on the front and operating contact mechanisms on the rear of the panels.
Control switches shall be suitable for operation on 600-volt AC or 250-volt
DC circuits. All such switches shall be capable of satisfactorily
withstanding a life test of at least 10,000 operations with rated current
flowing in the switch contacts. Selector switches shall be
maintained-contact type with the required number of positions, and shall
have round notched, or knurled handles. Ammeter switches shall not open
the secondary circuits of current transformers at any time. Instrument
switches for potential selection shall have oval handles.
2.8.13
[Power-Factor-Correction Capacitors
**************************************************************************
NOTES: Power factor correction capacitors should
not be used on the load side of solid state
starters. Motor control center manufacturers do not
normally contact the motor manufacturers, so where
possible the designer shall show KVAR ratings on the
drawings, coordinating these requirements with
actual motors used.
When power factor correction is not needed, delete
this paragraph.
**************************************************************************
Three-phase, delta-connected capacitors for power factor improvement shall
be rated [_____] volts, 60 Hz. [Capacitors shall have KVAR capacity as
shown on the drawings] [The capacitor KVAR capacity shall be selected to
achieve no less than [_____] percent leading nor more than [_____] percent
lagging power factor at nameplate value of motor full load current. The
SECTION 26 28 00.00 10
Page 29
KVAR capacity of the capacitors shall not be greater than that recommended
by the motor manufacturer or if no such recommendation exists, that value
which gives with a lagging power factor at no-load.] If size permits, the
capacitors shall be mounted in an adjacent compartment, or otherwise shall
be mounted separately and connected to the motor at the motor terminal
box. [For reduced voltage starters, the capacitors shall be separately
switched with a time-delayed contactor rated according to NEMA ICS 2 for
capacitor switching.]]
2.8.14
[Space for Mounting PLC's
**************************************************************************
NOTE: Delete this paragraph when PLC's are not used.
**************************************************************************
Space for mounting of Programmable Logic Controllers (PLC's) shall be
provided as indicated on the drawings.]
2.9
SWITCHBOARDS
**************************************************************************
NOTES: The switchboard specified below is not
intended for applications where the available fault
current is above 65,000 amps. Where drawout-type
breakers, and high short circuit current ratings are
desired, Section 26 22 00.00 10 480-VOLT STATION
SERVICE SWITCHGEAR AND TRANSFORMERS should be used.
The short-circuit current rating assigned to the
switchboard shall be in accordance with NEMA PB 2.
**************************************************************************
The switchboards shall be dead-front switchboards conforming to NEMA PB 2
and labeled under UL 891. The switchboards shall be completely enclosed
self-supporting metal structures with the required number of vertical panel
sections, buses, molded-case circuit breakers, [and other devices] as shown
on the drawings. Switchboards shall be fully rated for a short-circuit
current of [14,000] [22,000] [65,000] [_____] symmetrical amperes RMS AC.
2.9.1
Enclosure
**************************************************************************
NOTE: Mounting sills should be included for all new
construction to provide structural integrity. NEMA
PB2 90" height includes these sills.
**************************************************************************
Each switchboard enclosure shall be NEMA type [2] [3R], built with selected
smooth sheet steel panels of not less than 1.9 mm No. 14 gage. Exposed
panels on the front and ends shall have bent angle or channel edges with
all corner seams welded and ground smooth. The front outside surfaces
shall not be drilled or welded for the purpose of attaching wires or
mounting devices if such holes or fastenings will be visible from the
front. The front panels shall be made in sections flanged on four sides
and attached to the framework by screws and arranged for ready removal for
inspection or maintenance. [Rear access to the bus and device connections
shall be provided.] Ventilating openings shall be provided as required and
shall preferably be of the grille type. All ventilating openings shall be
provided with corrosion-resistant insect-proof screens on the inside.
SECTION 26 28 00.00 10
Page 30
[Each switchboard shall be provided with a channel iron base at front,
rear, and sides, with exposed ends covered by welded steel plates. Grout
holes shall be provided. The switchboard sections shall be bolted to the
base.] [Switchboards shall be mounted as shown on the drawings and
mounting materials shall be furnished as indicated.] All interior and
exterior steel parts shall be treated to inhibit corrosion and shall be
painted as specified in paragraph PAINTING.
2.9.2
Bus
**************************************************************************
NOTE: When either copper or aluminum bus is allowed
the manufacturers will generally provide the less
expensive aluminum. Use ASTM 317 when aluminum bus
is permitted. Silver plating allows for a greater
temperature rise on the bus.
**************************************************************************
All buses shall be of copper [or aluminum] and [all bolted splices and
connections between buses and for extensions or taps for equipment] shall
be tin or silver-plated [throughout]. Copper [or aluminum] bars and shapes
for bus conductors shall conform to the applicable requirements of
ASTM B187/B187M [, and ASTM B317/B317M]. All splices for field assembly
shall be bolted with at least two bolts and shall employ the use of
"Belleville" washers in the connection. Horizontal and vertical power
buses have minimum current ratings as shown on the drawings. The buses
shall be insulated for not less than 600 volts. Shop splices and tap
connections shall be brazed, pressure-welded or bolted. All splices for
field assembly shall be bolted. The buses shall be mounted on insulating
supports of wet process porcelain, glass polyester, or suitable molded
material, and shall be braced to withstand not less than [14,000] [22,000]
[65,000] [_____] symmetrical amperes ac.
2.9.3
[Grounding Bus
**************************************************************************
NOTE: Delete this paragraph when not required.
**************************************************************************
A copper [or aluminum] ground bus, rated not less than 300 amps, extending
the entire length of the assembled structure, shall be mounted near the
bottom of enclosure. A full clamp-type solderless copper or copper alloy
lug for No. 2/0 AWG stranded copper cable shall be provided at each end of
the bus for connection to the station grounding system.]
2.9.4
Components
Each switchboard shall be equipped with molded-case circuit breakers
conforming to paragraph MOLDED CASE CIRCUIT BREAKERS and with frame sizes,
trip ratings, and terminal connectors for attachment of outgoing power
cables as shown on the drawings. The circuit breakers shall be
individually stationary mounted, as shown on the drawings, and shall be
operable and removable from the front. Where shown on the drawings,
circuit breakers shall be enclosed in individual compartments. [The
group-mounted circuit breakers shall be provided complete with bus work in
an integrated assembly on the switchboard and shall conform to the
applicable requirements of paragraph PANELBOARDS.]
SECTION 26 28 00.00 10
Page 31
2.10
PANELBOARDS
**************************************************************************
NOTE: The short-circuit current rating assigned to
the panelboard shall be in accordance with NEMA PB 1.
**************************************************************************
Panelboards shall consist of assemblies of molded-case circuit breakers
with buses and terminal lugs for the control and protection of branch
circuits to motors, heating devices and other equipment operating at 480
volts ac or less. Panelboards shall be UL 67 labeled. "Loadcenter" type
panels are not acceptable. Panelboards shall be designed for installation
in surface-mounted or flush-mounted cabinets accessible from the front
only, as shown on the drawings. Panelboards shall be fully rated for a
short-circuit current of [14,000] [22,000] [_____] symmetrical amperes RMS
ac.
2.10.1
Enclosure
Enclosures shall meet the requirements of UL 50. All cabinets shall be
fabricated from sheet steel of not less than 3.5 mm No 10 gage if
flush-mounted or mounted outdoors, and not less than 2.7 mm No 12 gage if
surface-mounted indoors, with full seam-welded box ends. Cabinets mounted
outdoors or flush-mounted shall be hot-dipped galvanized after
fabrication. Cabinets shall be painted in accordance with paragraph
PAINTING. Outdoor cabinets shall be of NEMA 3R raintight and [conduit hubs
welded to the cabinet] [a removable steel plate 6 mm 1/4 inch thick in the
bottom for field drilling for conduit connections.] Front edges of
cabinets shall be form-flanged or fitted with structural shapes welded or
riveted to the sheet steel, for supporting the panelboard front. All
cabinets shall be so fabricated that no part of any surface on the finished
cabinet shall deviate from a true plane by more than 3 mm 1/8 inch. Holes
shall be provided in the back of indoor surface-mounted cabinets, with
outside spacers and inside stiffeners, for mounting the cabinets with a 13
mm 1/2 inch clear space between the back of the cabinet and the wall
surface. Flush doors shall be mounted on hinges that expose only the hinge
roll to view when the door is closed. Each door shall be fitted with a
combined catch and lock, except that doors over 600 mm 24 inches long shall
be provided with a three-point latch having a knob with a T-handle, and a
cylinder lock. Two keys shall be provided with each lock, and all locks
shall be keyed alike. Finished-head cap screws shall be provided for
mounting the panelboard fronts on the cabinets. Enclosure shall have
nameplates in accordance with paragraph NAMEPLATES. Directory holders,
containing a neatly typed or printed directory under a transparent cover,
shall be provided on the inside of panelboard doors.
2.10.2
Buses
**************************************************************************
NOTE: When either copper or aluminum bus is allowed
the manufacturers will generally provide the less
expensive aluminum. Use ASTM 317 when aluminum bus
is permitted. Silver plating the bus allows for
higher temperature rise and is not generally
required.
**************************************************************************
All panelboards shall be of the dead-front type with buses and circuit
breakers mounted on a plate or base for installation as a unit in a
SECTION 26 28 00.00 10
Page 32
cabinet. All buses shall be of copper [or aluminum] [and shall be tin or
silver-plated throughout]. Copper [or aluminum] bars and shapes for bus
conductors shall conform to the applicable requirements of ASTM B187/B187M
[, and ASTM B317/B317M]. The sizes of buses and the details of panelboard
construction shall meet or exceed the requirements of NEMA PB 1. Suitable
provisions shall be made for mounting the bus within panelboards and
adjusting their positions in the cabinets. Terminal lugs required to
accommodate the conductor sizes shown on the drawing, shall be provided for
all branch circuits larger than No. 10 AWG. A grounding lug suitable for
1/0 AWG wire shall be provided for each panelboard.
2.10.3
Components
Each branch circuit, and the main buses where so specified or shown on the
drawings, shall be equipped with molded-case circuit breakers having
overcurrent trip ratings as shown on the drawings. The circuit breakers
shall be of a type designed for bolted connection to buses in a panelboard
assembly, and shall meet the requirements of paragraph MOLDED CASE CIRCUIT
BREAKERS. Circuit breakers of the same frame size and rating shall be
interchangeable. [Bell alarm contacts shall be furnished as indicated on
the drawings and shall be wired to terminal blocks mounted in the cabinet.
Terminal blocks shall conform to requirements of paragraph TERMINAL BLOCKS.]
2.11
FACTORY TESTS
Each item of equipment supplied under this contract shall be given the
manufacturer's routine factory tests and tests as specified below, to
insure successful operation of all parts of the assemblies. All tests
required herein shall be witnessed by the Contracting Officer unless waived
in writing, and no equipment shall be shipped until it has been approved
for shipment by the Contracting Officer.
a.
Submit [6] [_____] copies of manufacturer's routine factory test
procedures and production line tests for all motor control centers and
switchboards, within a minimum of [14] [_____] days prior to the
proposed date of tests. Notify the Contracting Officer a minimum of
[14] [_____] days prior to the proposed date of the tests so that
arrangements can be made for the Contracting Officer to be present at
the tests.
b.
The factory test equipment and the test methods used shall conform to
the applicable NEMA Standards, and shall be subject to the approval of
the Contracting Officer. Submit [6] [_____] complete reproducible
copies of the factory inspection results and [6] [_____] complete
reproducible copies of the factory test results in booklet form,
including all plotted data curves, all test conditions, a listing of
test equipment complete with calibration certifications, and all
measurements taken.
c.
Report shall be signed and dated by the Contractor's and Contracting
Officer's Representatives. Reports of all witnessed tests shall be
signed by witnessing representatives of the Contractor and Contracting
Officer. The cost of performing all tests shall be borne by the
Contractor and shall be included in the prices bid in the schedule for
equipment.
SECTION 26 28 00.00 10
Page 33
2.11.1
Motor Control Centers Tests
2.11.1.1
Dielectric Tests
Each motor control center shall be completely assembled and given
dielectric tests in accordance with NEMA ICS 1.
2.11.1.2
Operational Tests
The correctness of operation of each air circuit breaker [or motor circuit
protector] and magnetic contactor and of all control devices, accessories
and indicating lamps, shall be checked. These checks shall be made at
rated voltage with power supplies to the main buses. All magnetic
contactors shall also be checked for proper operation with power at 90
percent of rated voltage.
2.11.1.3
Short Circuit Tests
If the unit is not UL labeled for the specified short circuit, the
Contractor may submit design tests demonstrating that satisfactory
short-circuit tests, as specified in NEMA ICS 2, have been made on a motor
control center of similar type of construction and having the same
available short circuit current at the motor terminals, including any motor
contributions, as the motor control centers specified to be furnished under
these specifications.
2.11.2
Switchboards Tests
2.11.2.1
Production Tests
Each switchboard shall be completely assembled and given applicable
production tests for assembled switchgear as specified in NEMA PB 2.
2.11.2.2
Short Circuit Tests
If the unit is not UL labeled for the specified short circuit, the
Contractor may submit design tests demonstrating that satisfactory
short-circuit tests have been made on a switchboard of similar type of
construction and of the same short-circuit rating as the switchboards
specified to be furnished under these specifications.
2.11.3
Panelboards Tests
Each panelboard shall be assembled with cabinet and front to the extent
necessary to check the fit and provisions for installing all parts in the
field. Each panelboard shall be given a dielectric test in accordance with
NEMA PB 1. All circuit breakers shall be operated to check mechanical
adjustments. All doors and locks shall be checked for door clearances and
fits and the performance of lock and latches.
2.12
PAINTING
Interior and exterior steel surfaces of equipment enclosures shall be
thoroughly cleaned and then receive a rust-inhibitive phosphatizing or
equivalent treatment prior to painting. Exterior surfaces shall be free
from holes, seams, dents, weld marks, loose scale or other imperfections.
Interior surfaces shall receive not less than one coat of
corrosion-resisting paint in accordance with the manufacturer's standard
practice. Exterior surfaces shall be primed, filled where necessary, and
SECTION 26 28 00.00 10
Page 34
given not less than two coats baked enamel with semigloss finish.
Equipment located indoors shall be ANSI Light Gray, [and equipment located
outdoors shall be ANSI [Light Grey] [Dark Gray].] All touch-up work shall
be done with manufacturer's coatings as supplied under paragraph SPARE
PARTS.
PART 3
EXECUTION (Not Applicable)
**************************************************************************
NOTE: PART 3 will be used for construction
contracts only; take care to prevent conflicts, gaps
or omissions.
**************************************************************************
-- End of Section --
SECTION 26 28 00.00 10
Page 35